Change of status

As of July 2014, Emdebian Grip stopped receiving updates to the unstable-grip distribution. Updates to the jessie-grip suite stopped some months before that. The last stable release of Emdebian Grip was 3.1 based on Debian GNU/Linux 7.1 Wheezy.

There will be no further updates of Emdebian Grip.

This information is retained for historical purposes but can be removed when wheezy is finally removed from the Debian mirrors (which will happen at some point before the next stable release after Debian Jessie 8.0).

Emdebian vision

In the Emdebian vision someone wishing to build a GNU / Linux based device would:

Port the linux kernel to their hardware (including writing any specific device drivers).

Select the prebuilt emdebian packages needed to support their application.

Package their application as Debian package(s) using Debian and Emdebian tools.

Thus Emdebian is a binary distribution for embedded devices (whereas most of the other contenders in this space are source distributions [of course being Debian and open source the source code is still available if required].

What emdebian does

In short, what EmDebian does is wrap around the regular debian package building tools to provide a more fine grained control over package selection, size, dependencies and content to enable creation of very small and efficient debian packages for use on naturally resource limited embedded targets.

We adapt Debian tools so you can build/cross-compile Debian packages or adapted packages with info on how to cross-build and build smaller packages.

We currently have two separate distributions - a post-processed binary-compatible distribution called Emdebian Grip for intermediate installations and a much smaller, much more involved cross-built distribution called Emdebian Crush. Each distribution can be further optimised for systems that would benefit from a static configuration by removing the maintainer scripts - this flavour is called Emdebian Baked.

Emdebian is experimenting with different approaches to cross-building and small-system-friendly packages in order to produce sustainable and robust long-term solutions. For cross-building there are two main approaches: Scratchbox (pkg), which allows cross-builds to appear to be native to the apps being built, and dpkg-cross (pkg) which allows conventional cross-builds to occur in a Debian-compatible way using emdebian-tools (pkg).

For package meta-data making packages more suitable for shrinking, two approaches are currently being investigated. The STAG approach uses a $(DEBIAN_DIR) directory to overlay changed info from the /debian directory, and is used by STAGE. The udeb approach of Debian-installer gives a tighter integration with Debian, with embedded packages having changed names so they can exist in the debian package namespace. Both mechanisms have pros and cons which are discussed in EmdebianMetaData.

New packages can be added to Grip using the emdebian-grip-server package. Adding new packages or new architectures to Crush is currently stalled until the EmdebianCodeAudit can be completed in order to resolve issues around packages with modified functionality.

Distribution status

Crush 2.0 is currently stalled due to build system problems - see EmdebianCrush for details of why, how this could be fixed and current experiments. If things stay as they are, there will be no release of Crush 2.0 (based on Debian 6.0 "squeeze"), instead development will target Crush 3.0 (based on Debian 7.0 - wheezy), reliant upon delivery of an implementation of Multiarch with sufficient support for cross-building.

Grip development is continuing. Grip 2.0 has been released alongside Debian 6.0 "squeeze" on six architectures (armel, mips, mipsel, i386, amd64, powerpc) and with some 2,000 packages. Work is ongoing alongside Debian for Emdebian Grip 3.0 based on Debian GNU/Linux 7.0 Wheezy.

Baked is as ready as it can be - Baked is primarily a do-it-yourself distribution but some starter packages are available.

Integration with Debian

There are various stages to integrating Emdebian into Debian, the process starts with Emdebian Grip - the binary compatible flavour.

Objectives

Wiki SiteMap

Frequently Asked Questions (FAQ)

Quick Start Guide

Tracker

EmdebianTracker - quick notes about issues that need a fix within the Emdebian packages (issues unrelated to cross building). e.g. a postinst script that calls a binary that is not available or with an unknown option, conflicts between packages that only show up when Essential is ignored, extra dependencies needed when Essential is ignored, etc.)

Code Audit

EmdebianCodeAudit - coordinating a complete audit of all patches required for Emdebian Crush 1.0 to support the implementation of the patches within the relevant Debian packages.

Cross Toolchains

Documentation

EmdebianPackagingGuidelines is a document explaining to package maintainers the sorts of things they should be aware of in their packaging to make their packages 'Embedded-friendly'. This includes cross-building and small-system-building.

How Grip relates to Crush

Building packages for Crush (for the EmdebianCodeAudit) now bases the final package on the Grip processing. i.e. the package is cross-built for Crush with limited changes and then the cross-built package is run through the Grip scripts to remove documentation, examples, handle Emdebian TDebs etc. This reduces the number of changes that need to be made in the patches for Crush, simplifying the patches and the build process. As the Audit proceeds, the patches necessary to allow the packages to be cross-built at all will be fed back to Debian via the BTS and included into the packages via maintainer uploads or, if necessary, with NMU's by Emdebian developers. The aim is to reduce the number of patches to only those necessary for the functional changes needed for Crush:

Avoid calling perl scripts that cannot be replaced by busybox

Avoid using perl in maintainer scripts

Reduce long dependency chains by turning off optional build components

Make maintainer scripts compatible with the busybox shell

This should allow many Debian packages to be cross-built without special tools and without external patches, with compliance to EmdebianPolicy being achieved after the cross-build is complete.

Multiarch and cross-compile

The goal is that both native and cross-compile behave the same, use files in the same location, use the same compiler flags and for all packages to be upgraded by the main system upgrades.

Current situation: all -*-cross debs, no multiarch

Soon: some -*-cross debs, some multiarch debs

When Multi-Arch starts to become available in the Debian archives, a version of dpkg will need to already exist which can understand how to install multiarch packages and that doesn't necessarily affect foreign arch packages. Installing a Multi-Arch 32bit package on a 64bit system is equivalent to installing a Multi-Arch armel package on an x86 system.

dpkg-cross will not convert multiarch packages, it simply ensures that the file exists to be installed alongside any remaining -cross packages.

pkg-config has a patch to support the --host option which is currently understood by the existing autoconf m4 macros.

Long term goal: no -*-cross debs, all multiarch

includes:

/usr/include + /usr/include/triplet

libraries:

/lib/triplet + /usr/lib/triplet

pkg-config:

/usr/lib/triplet/pkg-config

All -cross packages are explicitly not Multi-Arch compatible - dpkg-cross cannot be expected to convert a standard package to a pseudo-Multi-Arch cross package.